Question

The distance is measured on the topographic map. There are two methods of measuring distance on the toposheets,

(i) Direct-method,

(ii) Indirect method.

Measuring straight distance is a direct method and measuring through a winding course is an indirect method. Explain both the methods.

Answer 1

(i) To measure the straight distance:

To measure the shortest distance between two points on the topographic map along a straight line can be done easily with the help of a pair of divider. Keep the two pointed ends of the divider over line or two points which has to be measured and then carefully keep on scale. Note down the distance on the map in centimetres; then either with the help of the graphical scale which is provided below the toposheet or by using the statement scale distance can be measured in kilometres and metres.
e.g., two places are 5.6 km., apart on the map.
The scale is given 2 cm. = 1 km.
1 cm. = 1/2 km.
5.6 cm. = 1/2 × 5.6
= 2.8 km.
(ii) To measure winding course:

To measure a winding course route is complicated. It has to be measured with the help of a strip of paper or thread e.g., to measure a river in a toposheet take a piece of thread make a knot on one end. At the end of thread (close to knot) mark the point with pen at which you will begin to measure (point A). Put the thread along the line touching as far as possible to measure and keep on marking with ink at turns till the last point. Stretch the thread on the scale line, you will get the ground distance in kilometres and metres, writing the unit of measurement is always important e.g., if the distance calculated between two points is 3.3 km. If asked in kilometres the answer would be 3km., 300m. If asked in metres the answer would be 3300 metres.